This invention relates to printers and more particularly to an improved thermal printer mechanism for printing of labels or the like.
In the thermal printing of heat sensitive labels and the like the label stock is guided between a thermal print head and a driven platen roller. Electrical signals are provided to the print head to cause sequences of lines of desired characters to be formed on the label. Typically, thermal printers have the print head so mounted as to allow adjustment with respect to the platen roller to achieve the best available print quality by trial and error. Further, it is usual for thermal label printers to print labels of different widths and in so doing to maintain the label stock justified to one side of the print head for all widths. When the ratio of maximum to minimum label widths exceeds a certain point an adjustment may be required between the print head and the platen roller to obtain acceptable print quality for narrow labels. Typically, this adjustment causes the head to be tilted to closer proximity to the platen roller for narrow labels.
Thus, while thermal label printers provide significant advantages in many applications, known printers suffer from the disadvantages described above as well as others. For example, most thermal label printers in use today provide very limited access to the head and platen for cleaning and/or clearing of jammed label stock. This tends to encourage the operator to attempt to clear jammed stock with metal objects such as knives and screw drivers which can damage the print heads and platens.